A microcomputer controlling an electronic device requires power inputs by means of a plurality of different voltage levels depending on the type thereof, and the power-on order is set per type. In a case in which the power supplies are turned on in a different order from the predetermined power-on order, the microcomputer may malfunction.
In a power integrated circuit (IC) serving as a semiconductor integrated circuit generating power to be supplied to a microcomputer, the activation order of voltage regulators is set in a development stage so as to correspond to a microcomputer to be built in an applicable device. For this reason, the power IC cannot be applied to a microcomputer having a different power-on order. Therefore, it is difficult to use the power IC for a different device. Also, in a case in which the microcomputer to be built in the applicable device is changed, a new power IC needs to be designed.
As a conventional technique for dealing with this problem, there is a countermeasure in which timing of transmitting activation signals of respective voltage regulators is controlled to enable an activation order to be varied. For example, PTL 1 shown below discloses the following technique (refer to the abstract). “A sequence circuit controls activation timing of power supply circuits 1 to 4 based on count setting values CONT1 to CONT4 of the power supply circuits 1 to 4 from a selection circuit. A timing setting circuit outputs predetermined count setting values C81 to C84. An interface circuit reads out predetermined activation control data stored in an external storage device and outputs the data as count setting values C91 to C94. The selection circuit responds to a selection signal SEL to output the count setting values C81 to C84 or the count setting values C91 to C94 as the count setting values CONT1 to CONT4 to the sequence circuit.”